Differential microRNA Expression in USP8-Mutated and Wild-Type Corticotroph Pituitary Tumors Reflect the Difference in Protein Ubiquitination Processes.

Mateusz Bujko,Natalia Zeber-Lubecka,Jacek Kunicki,Monika Pekul,Jerzy Ostrowski,Agnieszka Paziewska,Natalia Rusetska,Andrzej Styk,Maria Maksymowicz,Joanna Boresowicz,Paulina Kober,Janusz A Siedlecki,Grzegorz Zielinski

doi:10.3390/jcm10030375

Abstract

Background: USP8 mutations are the most common driver changes in corticotroph pituitary tumors. They have direct effect on cells’ proteome through disturbance of ubiquitination process and also influence gene expression. The aim of this study was to compare microRNA profiles in USP8-mutated and wild-type tumors and determine the probable role of differential microRNA expression by integrative microRNA and mRNA analysis. Methods: Patients with Cushing’s disease (n = 28) and silent corticotroph tumors (n = 20) were included. USP8 mutations were identified with Sanger sequencing. MicroRNA and gene expression was determined with next-generation sequencing. Results: USP8-mutated patients with Cushing’s disease showed higher rate of clinical remission and trend towards lower tumor volume than wild-type patients. Comparison of microRNA profiles of USP8-mutated and wild-type tumors revealed 68 differentially expressed microRNAs. Their target genes were determined by in silico prediction and microRNA/mRNA correlation analysis. GeneSet Enrichment analysis of putative targets showed that the most significantly overrepresented genes are involved in protein ubiquitination-related processes. Only few microRNAs influence the expression of genes differentially expressed between USP8-mutated and wild-type tumors. Conclusions: Differences in microRNA expression in corticotropinomas stratified according to USP8 status reflect disturbed ubiquitination processes, but do not correspond to differences in gene expression between these tumors.

Highlights

Pituitary neuroendocrine tumors (PitNETs) represent about 10–20% of all intracranial neoplasms in adults
Corticotroph PitNETs commonly cause adrenocorticotropic hormone (ACTH)-dependent Cushing’s disease (CD); a notable proportion of tumors originated from corticotropic pituitary cells are endocrinologically non-functioning and classified as silent corticotroph tumors commonly referred to as silent corticotroph adenomas (SCA)
Patients with Cushing’s disease with and without USP8 mutations have a slightly different clinical profile according to previously published data [4,6,8,10,11,12,13,14,15]

Summary

Introduction

Pituitary neuroendocrine tumors (PitNETs) represent about 10–20% of all intracranial neoplasms in adults. Corticotroph PitNETs commonly cause ACTH-dependent Cushing’s disease (CD); a notable proportion of tumors originated from corticotropic pituitary cells are endocrinologically non-functioning and classified as silent corticotroph tumors commonly referred to as silent corticotroph adenomas (SCA). Both active and silent corticotroph PitNETs share a similar molecular profile [1,2]. Notable progress in the understanding of pathogenesis of CD has been made [3], including the discovery of recurrent USP8 mutations [4,5,6] These mutations are observed in approximately 30–40% of patients suffering from Cushing’s disease as well as in silent tumors [4,6,7,8,9]. MicroRNA and gene expression was determined with next-generation sequencing

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